1. Technical Field
The present invention relates to thermal control systems, and more particularly, but not by way of limitation, to low profile, rack mounted thermal control systems for cooling or heating equipment disposed in or in the vicinity of an equipment rack.
2. Background of Related Art
As the evolution of computers continued from mini-computers that filled entire rooms with equipment to PC modules similar to the personal computer known today, rack mounted equipment decreased in popularity. However, with the introduction of new electronic equipment, such as slice servers and laser systems, racks are returning to the computing environment. Rack mount enclosures are compact in design and allow for mounting of various components (e.g., servers, laser systems, chillers, etc.) in a stacked style configuration. Utilizing racks allows a user to include various rack mounted components in the rack, decreasing the foot print, while the components remain easily accessible for maintenance.
By mounting multiple components in a rack heat is increased, thereby causing deterioration and possible failure of many of the components. For example, most laser systems, such as those utilized for medical or industrial applications, generate a large amount of heat that requires cooling, via a chiller, in order to maintain proper function. In addition, many components, such as laser systems, perform poorly when subject to vibration and noise that many compressor-based chillers exhibit.
Conventional racks for the components as described herein are typically constructed of predetermined spatial parameters. For example, the height of an individual rack area, or “mounting space” adapted for conventional electronic components and the like is referred to in multiples of “U”. Each “U” (standing for the word “unit”) is equal to 1.75 inches. A 3 U height is therefore 5.25 inches. It is this “U” height that defines the standard rack mounting spatial relationship relative to a typical “19” inch wide mounting space. The “19” inch reference refers in actuality to the space allotted outside the mounting spaces for the equipment or component face plate. The inside of the mounting space generally has an inside dimension on the order of 17.5 inches. Using these spacing parameters, components and equipment mounted within such a rack are typically of a height that is a “U” multiple with a face panel on the order of 19 inches wide.
Although many components, such as servers and laser systems, are available in a height that is on the order of a “U” multiple for placement in the conventional rack, rack mounted chillers typically require a height of more than 3 U to offer effective cooling to the surrounding components. Some compressor-based units may require as much as an 8 U height. It should be noted, however, that such height is critical to space considerations of the overall rack. Conventional equipment racks only have a specified number of U's available and the higher the number of U's required for temperature control equipment, the fewer U's available for the necessary equipment. It is for this reason that special height considerations are important along with the functionality of the temperature control system.
Today's cooling technology typically includes passive cooling systems, compressor-based systems, and thermoelectric systems. In certain passive cooling systems, the air to be cooled is circulated over an air-to-air heat exchanger, which includes folded, finned heat exchangers, heat pipes, etc. The heat is then exchanged with the outside ambient air. As the amount of heat to be removed from the area increases, the size of the air-to-air heat exchanger increases. Compressor-based systems function by using a refrigerant and the cooling function is achieved by the compression and expansion of the refrigerant such as U.S. Patent Application Publication 2004/0221604, entitled “Liquid Cooling System for a Rack-mount Server System,” which is hereby incorporated by reference. These compressor-based systems typically weigh over seventy pounds and create unwanted vibrations. Thermoelectric temperature control systems use thermoelectric devices that pump heat using the Peltier effect. Typical thermoelectric devices incorporate a thermoelectric component that utilizes electrical current to absorb heat from one side of the component and dissipate that heat on the opposite side.
In addition to the above, instances arise where heating and/or temperature stabilization is equally important. For example, laser systems require a stable heat and temperature environment because the frequency of the light is dependent on the temperature of the diode. When rack-mounted systems that are vibrationally sensitive require precise temperature control, a compressor based system cannot be used. Thus, a more technologically complex scenario can evolve. A simple chiller is generally not capable of also performing a heating function without adding resistive elements. Thermal electric temperature control systems using thermal electric devices are, as described above, capable of both heating and cooling, low vibration, relatively high Coefficient Of Performance (“COP's”) (ability to remove heat), low noise, and low profile.
U.S. patent application Ser. No. 09/328,183 (the '183 patent application), now U.S. Pat. No. 6,935,409, assigned to the assignee of the present invention teaches a heating and cooling system with low vibration, relative high COP's, low noise and low profile. The low profile cooling system of the '183 patent application is, as stated therein, particularly well suited for cooling power amplifiers and other electronic components. In one embodiment, a heat transfer fluid is circulated in a closed loop to the area of components that generate heat. This approach allows the design, implementation and utilization of such thermoelectric cooling systems utilizing low profile extrusions capable of cooling high watt density sub assemblies such as a power amplifiers and filters commonly secured in rack mounted equipment or equipment that may be mounted around a conventional electronic component rack.
It would therefore be a distinct advantage relative to the above-described technology to provide a thermal control system that would be of low vibration, high efficiency, and yet easily mountable within a conventional rack with minimal “U” utilization.